• 접착 및 계면
• /
• 제8권4호
• /
• pp.14-22
• /
• 2007

본 연구에서는 페놀수지의 열안정성 그리고 glass braid/페놀수지 복합재료의 동역학적 열특성에 미치는 유리분말 및 액상 니트릴고무(NBR)의 영향을 열중량분석기와 동역학적 열분석기를 이용하여 조사하였다. 수용성 페놀수지에 충진된 유리분말과 NBR은 페놀수지의 열안정성과 복합재료의 저장탄성률 그리고 tan ${\delta}$ 변화에 중요한 영향을 미쳤다. 유리분말의 충진은 페놀수지의 열안정성을 향상시키는 반면, NBR의 존재는 특정 온도영역에서 페놀수지의 중량감소를 초래하였다. 충진제의 유 무에 따른 페놀수지의 열안정성은 경화온도뿐만 아니라 경화시간에도 의존하였다. 스트립형태의 glass braid/페놀수지 복합재료의 저장탄성률과 tan ${\delta}$의 변화는 유리분말과 NBR이 혼합된 매트릭스의 도입과 경화조건에 의해 크게 영향을 받았다.

• 한국세라믹학회지
• /
• 제54권6호
• /
• pp.484-491
• /
• 2017

Chalcogenide glasses have been investigated in their thermodynamic, structural, and optical properties for application in various opto-electronic devices. In this study, the $Sb_{20}Se_{80-x}Ge_x$ with x = 10, 15, 20, and 25 were selected to investigate the glass stability according to germanium ratios. The thermal, structural, and optical properties of these glasses were measured by differential scanning calorimetry (DSC), X-ray diffraction (XRD), and UV-Vis-IR Spectrophotometry, respectively. The DSC results revealed that $Ge_{20}Sb_{20}Se_{60}$ composition showing the best glass stability theoretically results due to a lower glass transition activation energy of 230 kJ/mol and higher crystallization activation energy of 260 kJ/mol. The structural and optical analyses of annealed thin films were carried out. The XRD analysis reveals obvious results associated with glass stabilities. The values of slope U, derived from optical analysis, offered information on the atomic and electronic configuration in Urbach tails, associated with the glass stability.

• 한국전기전자재료학회논문지
• /
• 제30권4호
• /
• pp.204-209
• /
• 2017

Thermal and structural stability in the glass transition region of chalcogenide glasses has been investigated in terms of thermodynamics for application to various optoelectronic devices. In this study, the compositions of $Ge_xSb_{20}Se_{80-x}$ (x = 10, 15, 20, 25, and 30) were selected to investigate the glass stability according to germanium ratios. The chalcogenide bulks were fabricated by using a traditional melt-quenching method. Thin films were deposited by a thermal evaporation system, maintaining the deposition ratio of $3{\sim}5{\AA}$ in order to have uniformity. The thermal and structural properties were measured by a differential scanning calorimeter (DSC) and X-ray diffraction (XRD). The DSC analysis provided thermal parameters and theoretical glass region stabilities. The XRD analysis supported the theoretical stabilities because of where the crystallization peak data occurred.

• Advances in Computational Design
• /
• 제7권3호
• /
• pp.253-279
• /
• 2022

This study investigated and predicted the Marshall stability of glass-fiber asphalt mix, carbon-fiber asphalt mix and glass-carbon-fiber asphalt (hybrid) mix by using machine learning techniques such as Artificial Neural Network (ANN), Support Vector Machine (SVM) and Random Forest(RF), The data was obtained from the experiments and the research articles. Assessment of results indicated that performance of the Artificial Neural Network (ANN) based model outperformed applied models in training and testing datasets with values of indices as; coefficient of correlation (CC) 0.8492 and 0.8234, mean absolute error (MAE) 2.0999 and 2.5408, root mean squared error (RMSE) 2.8541 and 3.3165, relative absolute error (RAE) 48.16% and 54.05%, relative squared error (RRSE) 53.14% and 57.39%, Willmott's index (WI) 0.7490 and 0.7011, Scattering index (SI) 0.4134 and 0.3702 and BIAS 0.3020 and 0.4300 for both training and testing stages respectively. The Taylor diagram also confirms that the ANN-based model outperforms the other models. Results of sensitivity analysis show that Carbon fiber has a major influence in predicting the Marshall stability. However, the carbon fiber (CF) followed by glass-carbon fiber (50GF:50CF) and the optimal combination CF + (50GF:50CF) are found to be most sensitive in predicting the Marshall stability of fibrous asphalt concrete.

• 한국세라믹학회지
• /
• 제52권2호
• /
• pp.114-118
• /
• 2015

$V_2O_5-P_2O_5-ZnO-Sb_2O_3$ glasses modified with BaO and $Al_2O_3$ are synthesized as a sealing material for large-scale dye-sensitized solar cells (DSSCs). A compositional study is performed in order to determine the glass that can be sintered below $500^{\circ}C$ with a high chemical stability against the electrolyte. The flow size of the glasses after the heat treatment and the glass stability are increased with the addition of $Al_2O_3$ and BaO, while the glass transition temperature is decreased. After the reaction with the electrolyte at $60^{\circ}C$ for 72 h, the addition of 5 mol% of BaO and 2 mol% of $Al_2O_3$ considerably enhances the chemical stability of the glass. X-ray diffraction (XRD) and scanning electron microscope (SEM) are used to examine the reaction between the electrolyte and glasses. The structural contribution of the additives is also investigated and discussed.

• Macromolecular Research
• /
• 제14권3호
• /
• pp.261-266
• /
• 2006

Blends of silicone rubber (VMQ) and liquid crystalline polymer (LCP) were prepared using a melt blending technique in the presence and absence of glass fiber and coupling agents. The effect of glass fiber and coupling agents on the thermal, dynamic mechanical, morphological pro-perties and cure characteristics of VMQ/LCP blends were studied. The vinyl silane coupling agent showed a significant effect on the above mentioned properties of VMQ/LCP blends by reacting at the interface between VMQ and LCP. The viscosity of the VMQ/LCP blends decreased with the addition of a coupling agent. A substantial improvement in storage modulus of VMQ/LCP blends was observed in the presence of glass fiber and coupling agents. However, as a coupling agent vinyl silane proved to be better than amine for the VMQ/LCP-glass-containing blends. The thermal stability of the pure silicone rubber was higher than those of the blends. This high thermal stability of silicone rubber was attributed to the Si-O-Si bonds. However, the thermal stability of the blends decreased further in the presence of a coupling agent, possibly due to a decrease in blend crystallinity.

• 대한치과교정학회지
• /
• 제45권3호
• /
• pp.130-135
• /
• 2015

Objective: In our previous study, glass-fiber-reinforced plastics (GFRPs) made from polycarbonate and glass fibers were prepared for esthetic orthodontic wires using pultrusion. These laboratory GFRP wires are more transparent than the commercially available nickel-titanium wire; however, an investigation of the color stability of GFRP during orthodontic treatment is needed. Accordingly, in the present study, the color stability of GFRP was assessed using colorimetry. Methods: Preparation of GFRP esthetic round wires (diameter: 0.45 mm [0.018 inch]) using pultrusion was described previously. Here, to investigate how the diameter of fiber reinforcement affects color stability, GFRPs were prepared by incorporating either $13-{\mu}m$ (GFRP-13) or $7-{\mu}m$ glass (GFRP-7) fibers. The color changes of GFRPs after 24 h, and following 1, 2, and 4 weeks of coffee immersion at $37^{\circ}C$, were measured by colorimetry. We evaluated the color stability of GFRPs by two evaluating units: the color difference (${\Delta}E^*$) and National Bureau of Standards (NBS). Results: After immersion, both GFRPs showed almost no visible color change. According to the colorimetry measurements, the ${\Delta}E^*$ values of GFRP-13 and GFRP-7 were 0.73-1.16, and 0.62-1.10, respectively. In accordance with NBS units, both GFRPs showed "slight" color changes. As a result, there were no significant differences in the ${\Delta}E^*$ values or NBS units for GFRP-13 or GFRP-7. Moreover, for both GFRPs, no significant differences were observed in any of the immersion periods. Conclusions: Our findings suggest that the GFRPs will maintain high color stability during orthodontic treatment, and are an attractive prospect as esthetic orthodontic wires.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
• /
• pp.220-222
• /
• 2004

Feasibility of BaO-ZnO-$B_2O_3$ (BZB) based glass system in the light of dielectric and thermal expansion properties are reported in the literature. Effects of addition of various types of ceramic fillers to the BZB-based glass on the thermochemical stability and mechanical properties were investigated in the present work. The studied filler-glass system demonstrated a capability to host various types of ceramic fillers to form thermochemically stable microcomposites at the processing temperature suitable for PDP systems. At the same time, mechanical strength of the filler-glass composites was much improved as compared to the glass itself These observations brighten the feasibility of the Pb-free BZB-based glass system as a host to employ various types of crystalline ceramic fillers so that it can be applied to barrier rib material in plasma display panels.

• 마이크로전자및패키징학회지
• /
• 제29권1호
• /
• pp.43-47
• /
• 2022

본 연구에서는 보일러 등에 적용을 하기 위하여 물속에 담군 채 가열할 수 있는 친환경 박막형 히터에 대한 결과를 보고한다. 장수명을 확보하기 위하여 소재 안정성이 높은 Mo 박막(40 nm)을 마그네트론 스퍼터법을 이용하여 Glass 기판상에 증착하였으며 후속 공정 진행 시 Mo 박막의 부식을 방지하기 위하여 상부에 ZnO 박막 (60 nm)을 형성하였다. 이후 투명 접착성을 가지는 PVB (Polyvinyl Butyral)를 이용하여 ZnO 박막 상부에 또 다른 Glass기판을 올려두고 열풍건조기 내에서 150℃의 온도에서 2시간동안 PVB를 경화시키며 접착시켜 Glass/Mo/ZnO/Glass 구조의 수중 히터를 완성하였다. 이렇게 제작한 발열체를 수중에 담근 후 발열 시 물의 온도가 2분 내 50℃까지 상승되는 것을 확인하였으며 미미한 수준의 저항증가가 발생하며 구조적 안정성 또한 확보되었다. 인가 전압의 세기에 따라 발열체의 온도가 제어되기 때문에 보일러에 적용할 때 사용자가 설정하는 온도를 용이하게 제어할 수 있을 것이라 기대된다. 마지막으로, 본 연구에서 제작한 박막형 히터는 반투명의 특성을 가져 심미성을 부여할 수 있어 제품의 부가가치를 더욱 높일 수 있을 것으로 기대된다.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권1호
• /
• pp.367-370
• /
• 2007

An EEFL with the sodium free alumino-silicate glass of high K and low $tan{\delta}$, has been investigated. As compared with borosilicate and the soda-lime EEFLs, the luminous efficiency as well as the pinhole stability of new EEFLs improves remarkably without blackening of $NaHg_2$.